1. Field of the Invention
Exemplary aspects of the present invention generally relate to a lubricant, a process unit including the lubricant, a transfer unit, and an image forming apparatus such as a copier, a printer, a facsimile machine, or a multi-functional system including a combination thereof, and more particularly, to a lubricant applicator that applies a lubricant
2. Description of the Background Art
Typically, image forming apparatuses, such as copiers, printers, facsimile machines, and multi-functional systems including a combination thereof, form a toner image on a photoreceptor, and then the toner image is transferred onto an intermediate transfer member.
Various attempts have been made to improve cleanability, transferability, and durability of the photoreceptor and the intermediate transfer member in the image forming apparatuses. One example of such attempts includes application of a lubricant such as zinc stearate to the photoreceptor, intermediate transfer belt, and so forth using a lubricant applicator.
FIG. 14 is a schematic diagram illustrating one example of a related-art lubricant applicator that applies the lubricant to the surface of the photoreceptor. A lubricant applicator 100 in FIG. 14 includes a lubricant 200 in solid form, an application brush 300, a lubricant holder 400, a biasing member 500, and a guide member 600. The application brush 300 serves as a lubricant application member. The lubricant holder 400 holds the lubricant 200. The biasing member 500 urges the lubricant 200 against the application brush 300 so that the lubricant 200 contacts the application brush 300. The guide member 600 guides the lubricant 200 in both approaching and separating from the application brush 300.
The application brush 300 is disposed close enough to contact the surface of a photoreceptor 700. As the application brush 300 rotates, the application brush 300 scrapes off the lubricant 200 and applies the scraped lubricant onto the surface of the photoreceptor 700.
Since the lubricant 200 is pressed against the application brush 300 by the biasing member 500, the lubricant 200 remains in contact with the application brush 300 even after the lubricant 200 is scraped off and consumed.
Various types of application brushes for applying the lubricant have been proposed. For example, Japanese Examined Patent Application No. H06-56539 (JP-H06-56539-B) proposes an application brush including a rod or a cylindrical core on which a strip member implanted with fibers is wound spirally in one direction. However, as illustrated in FIG. 15, there is a drawback to this configuration in that, when the application brush 300 consisting of the core, on which the strip member implanted with fibers is wound spirally in one direction, is rotated, a moving force F is generated in one way in an axial direction of the application brush 300 relative to the lubricant 200.
Such a moving force F causes a portion of the lubricant 200 or the lubricant holder 400 to contact the guide member 600, creating resistance. As a result, the pressure of the biasing member 500 changes at both ends of the lubricant 200, varying the amount of lubricant scraped by the application brush 300 at both ends of the lubricant 200, and thus the lubricant 200 is applied irregularly to the photoreceptor 700 in the axial direction of the application brush 300.
Referring to FIG. 16, a description is provided of the irregular force applied to a contact portion of the lubricant 200 and the application brush 300 toward the application brush 300. FIG. 16 is a schematic diagram illustrating the irregular force. As illustrated in FIG. 16, the force f is applied irregularly along the axial direction.
Furthermore, the irregular pressure at both ends of the lubricant 200 causes consumption of the lubricant 200 to increase at the end portion thereof where the pressure is high. On the other hand, when the end portion of the lubricant 200 where the pressure is low, the lubricant 200 is not adequately scraped (consumed). As a result, as illustrated in FIG. 17, irregular abrasion of the lubricant 200 occurs, hindering effective use of the lubricant 200. FIG. 17 is a schematic diagram illustrating irregular abrasion of the lubricant 200.
Referring now to FIG. 18, there is provided a schematic diagram illustrating a state in which the lubricant 200 is not parallel but inclined relative to the application brush 300. As illustrated in FIG. 18, when one end portion of the lubricant 200 or the lubricant holder 400 contacts the guide member 600 and is stuck, the lubricant 200 is pressed against the application brush 300 in an inclined manner. In such a case, the amount scraped by the application brush 300 at both ends of the lubricant 200 varies, thereby causing a problem similar to that described above, such as irregular application and abrasion of the lubricant 200.
Referring now to FIGS. 19A and 19B, there are provided schematic diagrams illustrating a state in which the lubricant remains parallel to the application brush 300 but one end portion of the lubricant 200 is offset or separated from the application brush 300. As illustrated in FIG. 19A, when the lubricant 200 drifts axially in one way, causing one end portion thereof to separate from the application brush 300, the separated portion of the lubricant 200 is not consumed. As a result, irregular abrasion occurs in the lubricant 200 as illustrated in FIG. 19B.
In view of the foregoing, for example, Japanese Patent Unexamined Application Publication 2007-140377 (JP-2007-140377-A) proposes using a plurality of rotary arms, which enables the lubricant to contact and separate from the application brush while maintaining the lubricant parallel to the application brush. In this configuration, the lubricant is pressed against the application brush evenly, thereby applying the lubricant evenly to the photoreceptor axially of the application brush.
However, there is a drawback in this configuration in that, equipped with a plurality of rotary arms, the number of parts increases, thereby complicating its manufacture and increasing its cost.
In view of the above, there is demand for a device capable of preventing irregular consumption and irregular application of the lubricant with yet a simple, uncomplicated configuration.